Titania is one of the most important titanium-based products, and it is also an important chemical feed stock. The majority of titanium resources are used for preparing titania. The consumption of titania is one of the symbols measuring the living standard of a country. There are rich resources of titanium and rare earth in China. Therefor, it is of great significance to study and develop the application fields of titanium, titania and rare earth elements.
For a supported metal catalyst, the interaction between metal and support is one of the factors that influence the activity and selectivity of the catalyst. The support plays an important role for the performance of the catalyst. S. T. Taustar (J. Am. Chem. Soc. 100, 170(1978)) discovered that the strong interaction between titania and metals (Strong Metal-Support Interaction, i.e., SMSI) greatly influences the performance of the catalyst. Therefore, studies on this subject have become an active field since then. As a new catalytic material, titania is being paid a great attention. People hope to obtain supports having better performances than alumina supports, which are widely used at present in this field. But up to now, research in this field still remains on theoretical and fundamental stage, and there is no reports with practical value.
In addition, in order to make titania an industrial catalyst support of practical value, it must have excellent physical and mechanical properties, and be feasible in economy, so as to satisfy various demands for different catalysts. The commercialized titania such as commercial titanium white can not satisfy the above-mentioned demands. The following catalysts, the supports of which contain titania, have not achieved the stage of industrial application because of the above-mentioned reasons.
European Patent Application 0339640A provides a co-precipitated alumina-titania composite which can be used as a catalyst and a catalyst support. The composite contains from 0.5 to 50wt. % of TiO.sub.2 based on the total weight of the composite. The average size of the titania particle, which is uniformly distributed in the bulk, is smaller than 50 .ANG.. When the co-precipitated alumina-titania composite is calcined at a temperature over 300.degree. C., the individual titania particle can not be distinguished from alumina matrix by X-ray diffraction. Since this alumina-titania composite is prepared by co-precipitation of water-soluble titanium salts (for example, TiCl.sub.3, TiOSO.sub.4 and TiOCl.sub.2) with water-soluble aluminum salts (for example, NaAlO.sub.2, KAlO.sub.2 or Al(NO.sub.3).sub.3, AlCl.sub.3 and Al.sub.2 (SO.sub.4).sub.3), the cost of raw materials is high, therefore it is not feasible in economy.
Other catalysts, the support of which contains titania, are reported in the following literature:
U.S. Pat. No. 4,992,406 (Mauldin et al.) provides a support for making catalysts which are used in the conversion of synthesis gas to hydrocarbons. The support contains titanium, in which an inorganic oxide binder selected from aluminum or zirconium is incorporated. The amount of the binder is in the range of from about 0.1 to 20% by weight based on the total weight of the titania-binder support. The provided titania-binder support has a pore volume ranging from about 0.2 cc/g to 0.5 cc/g, and a surface area ranging from about 8 m.sup.2 /g to about 70 m.sup.2 /g. A catalytically effective amount of metals such as cobalt, or cobalt plus an additional metal is dispersed on the support and thus the catalysts useful for Fischer-Tropsch synthesis are obtained.
U.S. Pat. No. 4962078 (Behrmann et al.) provides a cobalt-titanium catalyst, which is used for the production of hydrocarbons from synthesis gas, and its preparation process. The catalyst is prepared by dispersing and inlaying cobalt in a support as catalytically active layers. This support contains at least about 80% by weight of titania.
U.S. Pat. No. 5,130,285 (Wang et al.) provides a cobalt-molybdenum catalyst with a mixed titanium-zirconium-molybdenum oxide as a support. This catalyst is used for hydrodesulfurization of fuel oil. The support is prepared by adding aqueous ammonia to an anhydrous solution of titanium, zirconium and vanadium compounds such as chlorides to obtain a co-precipitate.
U.S. Pat. No. 4,196,101 (Wilson et al.) uses titanium tetrachloride or an organo-titanium compound such as titanium alkoxide, Ti(OR).sub.4, to prepare titanium-containing alumina pellets (tablets) and catalysts prepared with these pellets (tablets). The alumina pellets (tablets) contain from about 1 to 40% of titanium as TiO.sub.2 based on the total weight of aluminum (as Al.sub.2 O.sub.3) plus titanium (as TiO.sub.2).
U.S. Pat. No. 4,465,790 (Quayle) provides a hydrodenitrogenation catalyst comprising catalytic metals such as molybdenum and nickel on a support of co-precipitated alumina and titania (wherein the content of titania is in the range of from about 5 to 40%.
In addition, CN103900A (Application No. 89104390) and Japanese patent JP53095893 indicate that titania prepared by hydrolysis of titanyl chloride and titanium chloride etc., does not meet the demands for the industrial application not only in the performance but also in the economical consideration.
In addition to the above-mentioned unique SMSI effect, titania is ready to lose and gain oxygen easily, and can also adsorb hydrogen sulfide. Therefor, titania can be a support as well as an active component. It is very necessary to further study the titania support, and to seek for a simple and economical process for preparing it.